Certain pressure vessels, especially those used for testing purposes, require that specimens or equipment frequently be placed within, and removed from, the vessel. Entry ports are conventionally sealed by bolting a head onto a port flange with a multitude of bolts. A drip pan is provided beneath the port flange to prevent inadvertent spillage of water or other liquid coolant. The conventional method of opening and closing the port flange is done manually and is very time-consuming, mainly due to the large number of bolts that must be properly torqued to insure a proper seal. Further, due to the pressures within the pressure vessel, which can be up to 21 MPa (3000 pounds per square inch), a relatively very high preload is required to maintain an effective seal. This large preload requires a correspondingly large torque on the bolts in order to adequately press the seal rings of the vessel head against the port flange. Such a system demands exact rotational positioning of the head with respect to the vessel port so that the bolt openings within the head are concentric with a corresponding threaded section within the port. Also, the high torque necessary can lead to over torquing of the bolts and subsequent damage to either the head or the vessel port. Such operations can therefore be very time consuming and costly.
It is sometime desired to open and close the pressure vessel within a short time period. The most desirable device would also be one which is capable of remote operation to totally obviate the need for timeconsuming manual labor. Since the pressure vessel may contain liquid, the closure device should incorporate a drip pan to prevent spillage of any liquid or tive water contained within the vessel.
A hatch assembly having a rapid-action latching mechanism is described in U.S. Pat. No. 4,678,620 of which applicant is a co-inventor and is assigned to the present assignee. The hatch is pressed against the opening by means of a locking bolt having a chamfered surface being forced against a beveled surface of the hatch by a spring-loaded crankshaft arrangement. Although this provides for a relatively quick closing means as compared to a plurality of bolts, it still requires manual operation of a plurality of latching units. Furthermore, since it is a spring-loaded mechanism, it cannot provide the necessary preload required for sealing a pressurized vessel.
Since it is a pressurized vessel, it would be desirable as well to provide an automatic closure mechanism which would prevent the opening of the head while the vessel is still pressurized. This would prevent the possibility of injuring the operating personnel.
It is therefore an object of the present invention to provide a closure mechanism which provides for the quick sealing, opening, loading and unloading of a pressure vessel from a remote location.
It is another object of the present invention to provide a closure mechanism which is capable of providing a very large preload, on the order of about 53 MN to 62 MN (12 to 14 million pounds), on the closure head in order to provide an effective seal for the closure.
It is a further object of the present invention to provide a closure mechanism which incorporates a means to prevent the accidental spillage of contents when the head is removed.
It is a still further object of the present invention to provide a closure mechanism for a pressurized vessel which prevents the unlocking of the vessel head while the vessel is still pressurized.